Rotation dampers with which a viscous medium is arranged in an annular gap between the rotor and the housing are known in accordance with various embodiments. In the simplest case, the rotor is formed by a cylinder which is rotatably arranged in a cylindrical space. The viscous medium is located in an annular gap between the parts. It has also become known to design the rotor as a blade-like structure and to provide a gap between the ends of the blades and the cylindrical space in the housing. Usually the rotor is connected to an axle and a shaft which at one end is led out of the housing and is in working connection with a part to be dampened by means of a gearing. Such rotation dampers are for example employed in motor vehicles in order to brake the opening of the glove box cover, ash tray lid or the like. It is further known to provide such rotation dampers with a free-wheel in which the rotation of the rotor in one direction is effected essentially undampened. Finally, it has also become known to let such rotation dampers act directly upon the rotational axle of a pivotably mounted part. By means of this structure, the rotation brake may be integrated into the mounting of the pivotably mounted part thus not increasing the constructional dimensions of the part to be dampened. The latter rotation damper is known from DE 296 04 260.
Generally there is the requirement to construct such rotational dampers very small. On the other hand a certain braking moment must be able to be produced. There have thus been numerous suggestions which would permit the braking moment to become as large as possible, in that for example the shear surfaces engaged with the viscous medium are designed as large as possible. This for example may be effected in that several sleeve type sections of the rotor and housing mesh in an interlaced manner.
A problem develop, however, in connection with the filling of the viscous medium. With most rotation dampers the viscous medium is filled during the assembly of the damper. An end face closure plate in most cases forms the end closure. Such a manner of filling the dampers with the viscous medium is not practiced in connection with rotation dampers which must be assembled before filling, for example with those dampers with which the axle or the shaft are led out of the housing on both sides. With these dampers it is conceivable to provide an annular closure on the end face. However, due to the small width of the annular gap and also due to other reasons of design this is difficult to realize. Furthermore, the viscous medium must be deposited within the damper in accordance with a very precise metering procedures since otherwise the viscous medium is squeezed out or too much air remains in the inside of the housing. Both situations are seen to be disadvantageous since either they lead to contamination or the desired torque is not achieved due to the inclusion of air.